DESCRIPTION (Adapted from the abstract) Perinatal HIV transmission substantially contributes to infant and child morbidity and mortality in sub-Saharan Africa. In Malawi, the prevalence of HIV is about 30% among pregnant women and the infant mortality is more than 100 per 1000 live births. In industrialized countries use of antiretroviral drugs has remarkably reduced HIV mother to child transmission (MTCT). For example, in the U.S. use of a full (during pregnancy, intrapartum, and postpartum) regimen of AZT reduced perinatal HIV transmission by 67%, and in Thailand a shorter (during late pregnancy and intrapartum) regimen of AZT therapy reduced perinatal HIV transmission by 50%.. However, these regimens are expensive and are not practical to be recommended for women in Africa, where their first contact with the hospital is the labor room. A recent observational study from New York reported a reduction of 67% in perinatal transmission when women only received AZT at the time of delivery, or when only the baby received AZT during the first 48 hours after delivery. This finding has important policy implications if proved to be effective among breastfeeding women in Africa. The purpose of the proposed AIDS-FIRCA study is to determine in a traditionally breast-feeding community in Malawi: a) if a short prophylactic regimen of oral AZT given to the woman at delivery and to her baby during the first 48 hours of life, reduces the rate of HIV MTCT; b) if providing the newborn alone with oral AZT during the first 48 hours, reduces the rate of HIV MTCT. This is an intervention study. Women who consent to join the study will receive the intervention (AZT). These women will be compared with women concurrently recruited for a separate perinatal trial in the same hospital, a randomized double blinded, controlled phase III trial antibiotics to prevent chorioamnionitis-associated perinatal HIV transmission. This arrangement will reduce costs by utilizing the existing infra-structure of the on-going (parent) study. Assessing the efficacy of different approaches in the same population will determine the relative effectiveness of these interventions.